Anion sensor based on the indoaniline–thiourea system

A new chromogenic indoaniline–thiourea-based sensor was designed to recognize anions in an organic solvent through complementary intermolecular hydrogen bonding. Complexed anions cause significant disturbance to the intramolecular hydrogen-bonded structure of the sensor, which then induces color and UV–vis spectral changes. This sensor allows for selective colorimetric detection of tetrahedral oxoanions (HSO4− and H2PO4−).